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* [Bug c/32511] New: GCC inlines weak function
@ 2007-06-26 5:30 sabre at nondot dot org
2007-06-26 20:32 ` [Bug c/32511] " pinskia at gcc dot gnu dot org
` (10 more replies)
0 siblings, 11 replies; 12+ messages in thread
From: sabre at nondot dot org @ 2007-06-26 5:30 UTC (permalink / raw)
To: gcc-bugs
GCC generally doesn't inline weak functions, because their body may be
redefined by the linker: if the compiler inlined the call, the linker changing
the behavior of the function wouldn't change the inlined copy. For example,
GCC does not inline this:
void bar () __attribute__((weak));
void bar () {}
void foo() { bar(); }
However, GCC apparently overrides this if the inline keyword is added (and
potentially if the weak function is defined in a c++ class where it would be
implicit inline?). As such, it cause the following to be inlined:
inline void bar () __attribute__((weak));
void bar () {}
void foo() { bar(); }
However, again, this breaks the semantics of weak linkage. If bar is redefined
at link-time, the inlined copy is not updated. Because 'inline' is an
optimization request, not a requirement, it seems best for the compiler to
ignore the inline request in this case.
-Chris
--
Summary: GCC inlines weak function
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: sabre at nondot dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
@ 2007-06-26 20:32 ` pinskia at gcc dot gnu dot org
2008-02-17 19:38 ` hubicka at gcc dot gnu dot org
` (9 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-06-26 20:32 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pinskia at gcc dot gnu dot org 2007-06-26 20:32 -------
Considering inline candidate bar.
Inlining bar into foo.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
2007-06-26 20:32 ` [Bug c/32511] " pinskia at gcc dot gnu dot org
@ 2008-02-17 19:38 ` hubicka at gcc dot gnu dot org
2008-02-17 19:49 ` sabre at nondot dot org
` (8 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: hubicka at gcc dot gnu dot org @ 2008-02-17 19:38 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from hubicka at gcc dot gnu dot org 2008-02-17 19:37 -------
I think this is feature. If users explicitely declares as inline, then we do
that, otherwise we doesn't:
/* Don't auto-inline anything that might not be bound within
this unit of translation. */
else if (!DECL_DECLARED_INLINE_P (fn)
&& DECL_REPLACEABLE_P (fn))
inlinable = false;
otherwise we won't inline much e.g. with -fpic.
Honza
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
2007-06-26 20:32 ` [Bug c/32511] " pinskia at gcc dot gnu dot org
2008-02-17 19:38 ` hubicka at gcc dot gnu dot org
@ 2008-02-17 19:49 ` sabre at nondot dot org
2008-02-17 21:05 ` rguenth at gcc dot gnu dot org
` (7 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: sabre at nondot dot org @ 2008-02-17 19:49 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from sabre at nondot dot org 2008-02-17 19:48 -------
I understand the desire to optimize with -fpic, but miscompiling the code seems
unreasonable...
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
` (2 preceding siblings ...)
2008-02-17 19:49 ` sabre at nondot dot org
@ 2008-02-17 21:05 ` rguenth at gcc dot gnu dot org
2008-02-17 21:06 ` rguenth at gcc dot gnu dot org
` (6 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-02-17 21:05 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from rguenth at gcc dot gnu dot org 2008-02-17 21:05 -------
Well, I think we should error for the inline + weak combination, as it doesn't
make sense.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
` (3 preceding siblings ...)
2008-02-17 21:05 ` rguenth at gcc dot gnu dot org
@ 2008-02-17 21:06 ` rguenth at gcc dot gnu dot org
2008-02-18 7:36 ` sabre at nondot dot org
` (5 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-02-17 21:06 UTC (permalink / raw)
To: gcc-bugs
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu dot
| |org
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |accepts-invalid, wrong-code
Last reconfirmed|0000-00-00 00:00:00 |2008-02-17 21:05:49
date| |
Version|unknown |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
` (4 preceding siblings ...)
2008-02-17 21:06 ` rguenth at gcc dot gnu dot org
@ 2008-02-18 7:36 ` sabre at nondot dot org
2008-02-18 10:44 ` rguenth at gcc dot gnu dot org
` (4 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: sabre at nondot dot org @ 2008-02-18 7:36 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from sabre at nondot dot org 2008-02-18 07:35 -------
That works for me.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
` (5 preceding siblings ...)
2008-02-18 7:36 ` sabre at nondot dot org
@ 2008-02-18 10:44 ` rguenth at gcc dot gnu dot org
2008-03-27 16:35 ` rguenth at gcc dot gnu dot org
` (3 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-02-18 10:44 UTC (permalink / raw)
To: gcc-bugs
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Last reconfirmed|2008-02-17 21:05:49 |2008-02-18 10:44:02
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
` (6 preceding siblings ...)
2008-02-18 10:44 ` rguenth at gcc dot gnu dot org
@ 2008-03-27 16:35 ` rguenth at gcc dot gnu dot org
2008-03-27 16:36 ` rguenth at gcc dot gnu dot org
` (2 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-03-27 16:35 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from rguenth at gcc dot gnu dot org 2008-03-27 16:35 -------
Fixed.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
Target Milestone|--- |4.4.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
` (7 preceding siblings ...)
2008-03-27 16:35 ` rguenth at gcc dot gnu dot org
@ 2008-03-27 16:36 ` rguenth at gcc dot gnu dot org
2010-07-01 19:28 ` jason at gcc dot gnu dot org
2010-07-12 13:46 ` [Bug c/32511] [4.4/4.5/4.6 regression] GCC rejects inline+weak function jason at gcc dot gnu dot org
10 siblings, 0 replies; 12+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-03-27 16:36 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from rguenth at gcc dot gnu dot org 2008-03-27 16:35 -------
Subject: Bug 32511
Author: rguenth
Date: Thu Mar 27 16:34:55 2008
New Revision: 133646
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=133646
Log:
2008-03-27 Richard Guenther <rguenther@suse.de>
PR c/32511
* c-common.c (handle_weak_attribute): Reject combination of
weak and inline.
* gcc.dg/attr-weak-1.c: New testcase.
Added:
trunk/gcc/testsuite/gcc.dg/attr-weak-1.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/c-common.c
trunk/gcc/testsuite/ChangeLog
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] GCC inlines weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
` (8 preceding siblings ...)
2008-03-27 16:36 ` rguenth at gcc dot gnu dot org
@ 2010-07-01 19:28 ` jason at gcc dot gnu dot org
2010-07-12 13:46 ` [Bug c/32511] [4.4/4.5/4.6 regression] GCC rejects inline+weak function jason at gcc dot gnu dot org
10 siblings, 0 replies; 12+ messages in thread
From: jason at gcc dot gnu dot org @ 2010-07-01 19:28 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from jason at gcc dot gnu dot org 2010-07-01 19:28 -------
I think this change is wrong; weak definitions are also used to allow
definitions in multiple translation units without linker errors. C++ inlines
are emitted as weak symbols, and it seems rather odd to prohibit in C something
that the C++ front end does routinely.
--
jason at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jason at gcc dot gnu dot org
Status|RESOLVED |REOPENED
Resolution|FIXED |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c/32511] [4.4/4.5/4.6 regression] GCC rejects inline+weak function
2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
` (9 preceding siblings ...)
2010-07-01 19:28 ` jason at gcc dot gnu dot org
@ 2010-07-12 13:46 ` jason at gcc dot gnu dot org
10 siblings, 0 replies; 12+ messages in thread
From: jason at gcc dot gnu dot org @ 2010-07-12 13:46 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from jason at gcc dot gnu dot org 2010-07-12 13:46 -------
Marking as regression. Weak symbols have multiple uses: allowing replacement
is one, but they are also used to allow equivalent definitions in multiple
translation units without linker errors.
--
jason at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords|accepts-invalid, wrong-code |rejects-valid
Summary|GCC inlines weak function |[4.4/4.5/4.6 regression] GCC
| |rejects inline+weak function
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32511
^ permalink raw reply [flat|nested] 12+ messages in thread
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2007-06-26 5:30 [Bug c/32511] New: GCC inlines weak function sabre at nondot dot org
2007-06-26 20:32 ` [Bug c/32511] " pinskia at gcc dot gnu dot org
2008-02-17 19:38 ` hubicka at gcc dot gnu dot org
2008-02-17 19:49 ` sabre at nondot dot org
2008-02-17 21:05 ` rguenth at gcc dot gnu dot org
2008-02-17 21:06 ` rguenth at gcc dot gnu dot org
2008-02-18 7:36 ` sabre at nondot dot org
2008-02-18 10:44 ` rguenth at gcc dot gnu dot org
2008-03-27 16:35 ` rguenth at gcc dot gnu dot org
2008-03-27 16:36 ` rguenth at gcc dot gnu dot org
2010-07-01 19:28 ` jason at gcc dot gnu dot org
2010-07-12 13:46 ` [Bug c/32511] [4.4/4.5/4.6 regression] GCC rejects inline+weak function jason at gcc dot gnu dot org
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